The present invention relates to a drill rig assembly comprising a drill mast, a storage device for storing a number of drill pipes, in particular in a lying position, near said drill mast, a rotary head showing a rotating part arranged to be coupled to one extremity of a drill pipe and a fixed part mounted onto a rotary head trolley assembly which is movable up and down along said drill mast, and means for moving the trolley assembly and the rotary head along the drill mast to feed a string of drill pipes coupled to the rotary head in and optionally back out of the ground.
In practice, the handling of drill pipes from the storage device to the rotary head and vice versa to drill a hole in the ground, in particular a water well, is nearly always performed by means of human labour and sometimes by means of a cable winch. Such a handling of the drill pipes is very labour-intensive and may also be dangerous.
To solve this problem, it has been proposed to place the drill pipes vertically into a carrousel. By rotating the carrousel, the drill pipes can be positioned underneath the rotary head. A drawback of such a system is that only a limited number of drill pipes can be stored in the carrousel and that, due to the vertical position of the drill pipes in the carrousel, the stability of the drill rig is reduced. A further drawback is that loading and unloading the carrousel still requires a lot of time and is also dangerous because the drill pipes have to be manipulated also by hand, a winch or by another lifting device.
In BE-A-1006375, and also in WO 00/65193, a drill pipe handling arm has therefore been proposed which enables to take the horizontal drill pipes from the storage device and position them vertically underneath the rotary head. Such a drill pipe handling device offers a considerable saving of time. A drawback is however that there is still a risk that the drill pipes can fall from the handling arm causing thus a very dangerous situation. The drill pipe handling device is further laborious to operate and especially quite expensive to produce.
An object of the present invention is therefore to provide a new drill rig assembly comprising a drill pipe handling system which can be produced at a lower cost and which enables to transfer the drill pipes relatively quickly, easily and safely from the storage device to the rotary head and vice versa and this without or with a minimum manual intervention.
To this end, the drill rig assembly according to the present invention is characterised in that the rotary head is provided with a clamping assembly provided to hold a drill pipe with its extremity which is arranged to be coupled, in particular screwed, to the rotating part of the rotary head, and in that the drill rig assembly further comprises means for moving the rotary head with respect to said rotary head trolley assembly, which means are arranged, together with the means for moving the rotary head trolley assembly along the drill mast, to enable the rotary head to clamp with said clamping assembly a drill pipe in the storage device and to position the drill pipe on top of the drill string, substantially in axial alignment thereto.
In the drill rig assembly according to the invention, no separate drill pipe handling device has to be provided since the rotary head itself is used to handle the drill pipes. This rotary head has only to be provided with a suitable clamping assembly to hold the drill pipes and the necessary movements of the rotary head to take a drill pipe from the storage device and bring it to the string of drill pipes which are being drilled into the ground. Apart from the usual movement up and down along the drill mast, a pivotal movement of the rotary head with respect to the trolley assembly may for example be sufficient. Compared to a separate drill, pipe handling device, the system according to the invention requires less costs, in particular since a large part of the required movements of the rotary head are already available in the conventional drill rigs. Moreover, no transfer of the drill pipes from the drill pipe handling device to the rotary head or vice versa is required any more, resulting not only in a less complex system but also in a reduction of the operating time and a gain in security considering the fact that the drill pipes are not handled by hand and are always tight to the drill head.
In a preferred embodiment of the drill rig assembly according to the invention, said clamping assembly comprises first and second mutually co-operating clamping means to clamp the drill pipe between them, the first clamping means comprising a tubular portion arranged to partially enclose the extremity of the drill pipe to be clamped therein and showing a longitudinal slit enabling said extremity of the drill pipe to be inserted laterally into this tubular portion, said tubular portion in particular enclosing the extremity of the drill pipe over an angle of at least 180xc2x0, preferably over an angle of more than 180xc2x0.
An advantage of this embodiment is that the extremity of the drill pipes can simple be inserted into the tubular portion of the first clamping means by lowering the rotary head, having the slit in this tubular portion directed downwards, onto the extremity of the drill pipe.